Spacecraft, including satellites and other space vehicles, orbit the earth performing a multitude of different functions and operations, such as links in telecommunications systems, photographing selected geographical areas, sensing or measuring different conditions on the earth, and monitoring weather patterns and conditions, to name a few. The attitude of these spacecraft or orientation relative to the earth and the nature of the orbit may be critical to the proper performance of these spacecraft. Accordingly, being able to accurately determine the attitude, position, orbit, velocity as well as other operating conditions or parameters and being able to control or change these parameters can be highly important. In the case of geostationary or GEO spacecraft or satellites which remain fixed in orbit relative to a location on the earth, determining and controlling the attitude, position, orbit and other operating parameters may be imperative for proper operation. GPS satellites may be used for determining the orbit of spacecraft but use of GPS satellites can present difficulties at time. At GEO orbit, GPS satellite visibility to the GEO orbit spacecraft can sometimes be poor. At other times when a large number of GPS satellites are visible, the geometries or relative positioning of these satellites with respect to the GEO spacecraft may be poor for orbit determination of the GEO spacecraft. Additionally, GEO orbit determination and control in the presence of thruster maneuvers can present additional challenges.